Dark matter is perhaps the most frustrating substance we know. Invisible to all forms of light, we detect its presence through its gravitational influence alone. That's insufficient, though: physicists and astronomers alike would like to know what it is. Yet so far, we're better able to say what it isn't: it's not the stuff of normal matter (electrons, quarks) or other particles we know about, like neutrinos.

Could dark matter be the stuff that black holes are made up of? They are invisible must have lots of gravitational influence.

What if dark matter is actually anti-matter? This would explain why it doesn't react with ordinary matter, because it would be annihilated long before it ever reached the detectors. Or maybe I'm misunderstanding how dark matter is different than anti-matter.

What if dark matter is actually anti-matter? This would explain why it doesn't react with ordinary matter, because it would be annihilated long before it ever reached the detectors. Or maybe I'm misunderstanding how dark matter is different than anti-matter.

If dark matter is anti-matter, we would expect to be able to view places in the universe where dark matter and matter collide and produce light. (That light energy could be in the form of visible light, or could be somewhere else on the electromagnetic spectrum.) Antimatter does interact with regular matter in the form of colliding and annhilating into pure energy.

Black holes are also not likely to be the main sources of dark matter--though there probably is dark matter that accumulates around a black hole just like regular old matter does. The influence of a black hole is primarily felt through its gravitational force, which, as the article stated, is the only thing we're sure has an effect upon dark matter. The article down below talks about the black hole link.

This really reminds me of the search for luminiferous aether in the late 19th century. If I were to return to theoretical physics (an undergrad degree I have never directly used) I think I would start looking for an error in the standard model that vanishes at "small" scales, much like relativistic effect vanish under the slow-speed low-mass/energy conditions to yield Newtonian physics.

Maybe there is something out there, but to me dark matter seems much too smooth and evenly distributed for something influenced by gravity. If there are wimps, I want to understand why they are not lumpy like the rest of the observable universe.

Maybe there is something out there, but to me dark matter seems much too smooth and evenly distributed for something influenced by gravity. If there are wimps, I want to understand why they are not lumpy like the rest of the observable universe.

Regular matter can clump only by banging into other regular matter, shedding energy and momentum in the process. Else, conservation of energy/momentum prevents it from clumping, and you'd get just a whirling disk of evenly distributed dust for all eternity. Dark matter is weakly interacting, and so cannot lose significant amounts of energy this way.

This really reminds me of the search for luminiferous aether in the late 19th century. If I were to return to theoretical physics (an undergrad degree I have never directly used) I think I would start looking for an error in the standard model that vanishes at "small" scales, much like relativistic effect vanish under the slow-speed low-mass/energy conditions to yield Newtonian physics.

I've made that exact comparison before (as well as comparisons to phlogiston, but those are less relevant than they used to be). Personally, I'm rooting for STVG as an alternative theory which doesn't require dark matter to exist.

What if dark matter is actually anti-matter? This would explain why it doesn't react with ordinary matter, because it would be annihilated long before it ever reached the detectors.

If 26% of the mass-energy of the universe were anti-matter compared to the 4% ordinary matter, everything would have been annihilated some time ago. We can detect antimatter in cosmic rays, and they make up about 1% of the particles coming in. Anti-matter is the same as ordinary matter, except it's anti-, so it interacts with itself in a similar way and can produce light.

Any chance dark matter exists near but not in our four dimensional space? That way, it could possibly interact with 4 space by gravity, however, not get close enough for electromagnetic, strong or weak interaction.

Maybe there is something out there, but to me dark matter seems much too smooth and evenly distributed for something influenced by gravity. If there are wimps, I want to understand why they are not lumpy like the rest of the observable universe.

The easiest answer is if there is no self-coupling. Maybe dark matter doesn't interact with itself or regular matter except via gravity. Therefore, very few collisions and no agglomerations. Maybe it just oscillates through and rotates around regular matter clumps like stars and galaxies.

Which makes me wonder how dark matter might interact with black holes. Perhaps you just get a large annulus of dark matter encircling the event horizon? If so, that would make a black hole look more massive than it actually is, but that's about it.

If 26% of the mass-energy of the universe were anti-matter compared to the 4% ordinary matter, everything would have been annihilated some time ago. We can detect antimatter in cosmic rays, and they make up about 1% of the particles coming in. Anti-matter is the same as ordinary matter, except it's anti-, so it interacts with itself in a similar way and can produce light.

I would think, only 52 percent of everything would be annihilated. The rest would just be energetically rearranged.

You know what I hate? When peopel with no scientific background at all come up these random 'theories' that are little more then nonsensical babbling.

Please, please please, stop doing that.

We know the Standard Model is incomplete. I am not a fan of String Theory as it would not be hard to come up with a String Theory that would describe any possible universe with any possible set of physical constants. More importantly, I do not believe there is any reasonable test that could disprove String Theory.

When all the current theories are, at best wrong, it is time to start throwing random stuff out to see what sticks. If something stupid fits, find a way to test it.

Dark matter - a public works project for scientists who can't make it in industry.

I hate to tell you this, scientists that work on theoretical science, sometimes using billions of dollars worth of equipment are the rock stars of science. Those who work in the private sector, designing a better toilet plunger, not so much.

And so the church of scienceology started. with the loyal followers of science uprising against anyone who questions their favourite paradigm.

Send all who question whether a scientist gets it right to Kepplar 78b. Praise be to dogma!

1) Define science: the self-questioning field that considers all possibilities, rejecting those with no basis.2) You, smarter than science, consider ALL things, even non-scientific things, in order to truly consider all possibilities.3) a) You reject baseless and disproven 'possibilities' => See 1).3) b) You accept at least one baseless or disproven 'possibility' => See Creationism.

Black holes are also not likely to be the main sources of dark matter--though there probably is dark matter that accumulates around a black hole just like regular old matter does. The influence of a black hole is primarily felt through its gravitational force, which, as the article stated, is the only thing we're sure has an effect upon dark matter. The article down below talks about the black hole link.

Maybe there is something out there, but to me dark matter seems much too smooth and evenly distributed for something influenced by gravity. If there are wimps, I want to understand why they are not lumpy like the rest of the observable universe.

Regular matter can clump only by banging into other regular matter, shedding energy and momentum in the process. Else, conservation of energy/momentum prevents it from clumping, and you'd get just a whirling disk of evenly distributed dust for all eternity. Dark matter is weakly interacting, and so cannot lose significant amounts of energy this way.

I'm wondering if the reason we can't detect dark matter directly is that it gets pushed out to the edges of our solar system. Perhaps it has low enough mass that even small particles flying off from the sun could pull it to the outer edges. The effect would be similar to an air amplifier, or how a balloon gets pulled toward a faucet of running water. Except with dark matter the gravity from the Sun's particles is doing the accelerating or pulling of the dark matter.

Any other dark matter not pushed or pulled to the edge of our solar system is probably down in the center of all the planets. If our Sun isn't producing dark matter then any from outside would never make it past the outer planets.

Man you guys get pretty defensive pretty quick. It's not even political or religious, I really don't get the attitudes.

And this particular thread is exactly the time and place for crazy theories on the universe. It's actually on topic, for a change. I know it annoys you real scientists, but this one time, chill.

Here's mine: They can't find the WIMPs because there aren't any. The gravity is there, obviously, but the assumption that it must be generated by mass, distributed according to the inverse square of the distance law, is faulty.

Yes, it's generated by mass, but the mass is in the black hole. That's what happens to the mass inside the singularity that our present physics can't account for. Dark Gravity is where it 'goes'.

Now, how exactly the gravity is distributed the way it is; so far away, and dispersed from the black hole; I of course don't know. The implication is that another dimension is at play here.

You see, I'm not dismissing Eisenstein; I'm slavishly adhering to him. The singularity can't exist in our physical universe, therefore I'm suggesting that it doesn't. The extra mass has to go somewhere, but the standard model still holds.

So, the extra mass is forced into another dimension. String theory anyone? But the mass is still 'there', and there will be gravity from it; there's no getting around that. 'There' is just not confined to the center of the black hole, not when you're talking about another dimension(s). So we see the gravity dispersed all around the galaxy.

That's not even crazy, what I just said complies with our current observations. Here's crazy: In order for that gravity to 'come out' from whatever string theory dimension the singularity mass is held in, it has to encounter normal matter outside the singularity. In other words, the stars and planets themselves emanate this extra gravity, in addition to their own.

This would account for the dispersal we see, to a point. But it would also fundamentally change our understanding of the gravitational constant, and I don't like that part. Better would be that the strings just carry the gravity away, and it's spilling out as it's carried away from the singularity. I say carried, which is somewhat misleading; I don't believe any time elapses. I believe the gravitational effect is instant. Also, I believe there there would still be somewhat of a square of the distance rule at play here, but it's galaxy-wide, and I guess you need to bring string theory into it to figure it out.

You know what I hate? When peopel with no scientific background at all come up these random 'theories' that are little more then nonsensical babbling.

Please, please please, stop doing that.

I frequently find them amusing. Also its a chance to spread a little scientific knowledge. Some will be young people that don't have the training yet that may be inspired to a career in science. Please don't discourage random conjecture. Especially about something as bizarre as dark matter or dark energy.

The evidence is the gravity. The gravity is easily measured; there's more there than the mass we can see to account for it. A lot more. As far as we know, gravity comes from mass, and mass only. It must be there somewhere.

I'm wondering if the reason we can't detect dark matter directly is that it gets pushed out to the edges of our solar system.

This has all been calculated. The amount of dark matter that theory predicts being in the vicinity of our solar system would have a completely undetectable--by our current best instruments--effect on the motions of any planets or the sun, by a few orders of magnitude. This is a galaxy-sized-and-larger problem.

This is the sort of thing dorl was complaining about: Wild theories already disproven, explanations that fail to explain any of the existing evidence or even anything useful, gibberish that any scientist in this field has already heard a hundred times.

I know, It's a pop-sci article. It's not going to be able to have all the information. And I don't want to tell people not to imagine; imagination is how we get new science. Curiosity, sharing, all of that is important to progress. Just maybe at least go read the Wikipedia page first? Google to see if your "new" theory is, actually, new? I dunno.

It was first discovered because galaxies don't spin at the rates expected at different distances from the center. A normal gravitational system, say for example the solar system, objects closer in orbit the center of mass much quicker than objects further out. That is why Mars orbit is much longer than Earths and Mercury is much quicker than Earth. Careful measurement of galactic edges showed them to be orbiting as if they were in the middle of a much larger galaxy. Other experiments show its effect in gravitational lensing. So every characteristic of mass is found in dark matter BUT NO OTHER CHARACTERISTIC has been found to date despite many many careful observations and experiments.